Genentech Inc. on Monday said its experimental drug Lucentis, used to treat the leading cause of Blindness in older adults, was shown to significantly improve vision in an ongoing late-stage trial.

Preliminary trial results also show that Lucentis met the primary goal of stabilizing vision in patients with wet Age-related macular degeneration, which afflicts an estimated 1.2 million Americans, mostly over the age of 50.

The South San Francisco, California-based company said about 95 percent of patients given monthly eye injections of Lucentis maintained or improved their vision after a year, compared with 62 percent of patients in the study’s control arm.

Genentech said patients treated with Lucentis had, on average, a significant improvement in vision compared to the beginning of the study, while patients in the control group had, on average, substantial deterioration.

By contrast, existing treatments such as Macugen sold by Pfizer Inc. and Eyetech Pharmaceuticals Inc., and Visudyne sold by QLT Inc. and Novartis have been able to improve vision in only a relatively small percentage of patients.

“These results basically tell us that Lucentis is going to take this market away,” said Andrew McDonald, an analyst with ThinkEquity Partners.

He said Lucentis resulted in a 53 percent relative improvement compared to a placebo, while a similar late-stage trial of Macugen showed a 27 percent relative improvement.

The Genentech trial, however, only included patients with the two most common forms of the disease.

“This is preliminary data ... We can expect very close examination of the detailed data,” said Steven Salamon, an analyst with Infinium, a life sciences-focused investment banking boutique. He rates Eyetech shares “underperform.”

In a statement, Eyetech and Pfizer cautioned that clinical trial data must be interpreted based on similar patient demographics. Lucentis and Macugen trials were in different patient populations and used different protocols, they said.

Side effects in the Lucentis trial included hemorrhage of the eye membrane, eye pain and vitreous floaters.

Genentech said it will report full results from the first year of the 716-patient trial at a medical meeting in July. The two-year trial, which began in December 2003, is still underway.

The company, along with development partner Novartis Pharma AG, is conducting additional pivotal-stage trials, including comparing the drug to Visudyne, which is injected into the arm and activated by a laser shined on the eye.

Genentech does not yet know when it will seek regulatory approval for the drug, company spokeswoman Dawn Kalmar said.

McDonald said he expects Lucentis to reach the market late next year, after which sales of Macugen will begin to drop.

Wet AMD is caused by an over-proliferation of blood vessels under the macula, the central part of the retina. Lucentis is an antibody designed to block formation of those blood vessels.

Genentech’s share price has nearly doubled since mid-March when the company reported that its Colon cancer drug, Avastin, is effective against lung cancer. Avastin cuts off blood vessel formation to cancer tumors.